Thermoplastic or thermosetting polymeric material or resin is typically processed in processing equipment, such as injection molders or extruders. The polymer materials typically introduced or fed into the processing equipment are in a granular or pellet form which is subsequently heated above its melting point and formed into a final product. As known in the art, the polymeric materials can be colored with pigments or other colorants in order to provide the final product with a desired appearance.
The manufacturers and processors frequently need to change the kinds and colors of resin in a single processing equipment in accordance with the market needs. Such changes in the kinds and colors of resin result in a waste of time and materials and correspondingly, there has been desired the development of a method for effective cleaning of the interior of polymer processing equipment, such as the molding machine, in order to improve production efficacy and quality of the resulting products.
Furthermore, the processing of polymers and particularly polymers that are polar and/or have an affinity to metal surfaces when melted, can result in build-up of the polymer in the polymer processing equipment (e.g., on a screw or barrel, such as on an extruder, or in a dye, an adapter, or other component of the processing equipment). The build-up of polymer, over time, may result in polymer being exposed to heat for an extended period of time, such that some of the polymer changes in color or flow characteristics. As a consequence, a part being produced using a process that includes a step of processing the polymer through the processing equipment may be discolored, have non-uniform color (e.g., black specks) or have defects resulting from the change in flow characteristics. As one example, polymer that has been exposed to heat for an extended time may result in particles that block the flow of material, such as through a die.
Various methods are known in the art to clean the polymer processing equipment after running a processing resin, so that the equipment does not need to be dismantled and manually cleaned. The cleaning may be done with a neat resin or with another processing resin to be processed into parts. Cleaning agents are commercially available and are routinely employed to remove certain processing resins. Cleaning agents also find utility when transition between processing of a first processing resin to a second processing resin. Cleaning agents disclosed in the prior art include those that employ abrasives (US 2002/0193267) or a chain scission catalyst (US 2011/0012275) which renders the cleaning agent reactive and facilitates the removing of residual polymer from the processing equipment. Further cleaning agents are for example known from JP 2011-246609, JP H1081898, JP H09208754 and JP 2002-003666.
Despite the advances in cleaning agents, there continues to be a need for new cleaning agents that can remove a broad range of polymers, such that the number of different cleaning agents needed by a polymer processor is reduced.
There is also a continued need for cleaning agents that clean more efficiently such that the amount of unproductive time on the processing equipment is reduced, the amount of waste generated during the cleaning is minimized, or both.